1. Field of the Invention
This invention relates to machines for handling materials, in particular machines which can be used for loading or digging.
2. Description of the Prior Art
Material handling machines for use on construction sites usually have crawler tracks or large-diameter wheels and are usually designed to carry out a given task such as digging, loading, or pallet-lifting. If a machine is designed to carry out two tasks, one of these will be the primary task, and the secondary task will be carried out less efficiently because of physical design constraints.
In material handling machines in which both the front and rear wheels are driven, an engine mounted at an arbitrary position on the chassis usually drives a hydraulic pump which supplies a hydraulic circuit feeding hydraulic motors associated with the wheels. Such a hydraulic transmission is very inefficient compared with a mechanical transmission.
One known machine which is in use has a rear-mounted backhoe, a front-mounted engine, and a front-mounted linkage carrying a loader bucket. This has the disadvantages of poor loader visibility (the operator's line of sight is obstructed by the hood of the engine) and poor maneuverability (the linkage obstructs the turning of the front wheels). A similar known machine improves maneuverability by using smaller front wheels, but this compromises stability and load capacity.
Another known machine has a rear-mounted engine and a front-mounted linkage carrying a loader bucker, pallet forks, or a telescopic arm. Forward visibility is good, but a backhoe has to be omitted because of the rear-mounted engine.
Another known machine also has a rear-mounted engine. A telescopic boom extends forwards from a rear pivotal mounting, along the center-line of the machine, the operator's cab being mounted at one side. The extremity of the boom carries a loader bucket or pallet forks. Again, forward visibility is good but a backhoe cannot be fitted at the rear.